1. Field of the Invention
The present invention relates to an apparatus for transferring circuit components such as electric-circuit or electronic-circuit components, and particularly to the art of rotating each of a plurality of component holders of the apparatus about an axis line thereof.
2. Prior Art Statement
Japanese Patent Application laid open for opposition under Publication No. 62(1987)-13838 discloses a circuit-component ("CC") transferring device which is employed as a CC mounting device in a CC mounting system which mounts circuit components ("CCs") on a circuit substrate ("CS") such as a printed circuit board ("PCB").
The above CC transferring device includes a plurality of component holders, and an intermittently rotatable body which holds the component holders and which is supported by a base member such that the rotatable body is intermittently rotatable about an axis line thereof. The rotatable body has a plurality of holding holes which are formed on a circle whose center rides on the axis line, such that the holding holes are equiangularly spaced from each other about the axis line, and in which a plurality of sleeves are fitted, respectively, such that each of the sleeves is not movable in an axial direction thereof and is rotatable about an axis line thereof relative to the rotatable body. Each of the component holders includes a nozzle holding member which is fitted in a corresponding one of the sleeves such that the nozzle holding member is movable in an axial direction thereof and is not rotatable about an axis line thereof relative to the corresponding sleeve.
Each of the nozzle holding members holds, at a lower end thereof, a component suction nozzle. An engaging pin is fitted in an upper portion of each nozzle holding member such that the pin extends through the holding member in a diametrical direction thereof, and also is fitted in a recess which is formed in the sleeve such that the recess extends in the axial direction thereof. Thus, the nozzle holding member is rotatable together with the sleeve relative to the rotatable body, and is movable relative to the sleeve in the axial direction thereof. Each of the sleeves has a lower end portion which projects downward from the rotatable body and to which a timing pulley is fixed. A common timing belt is around on the respective timing pulleys of the sleeves. This timing belt is also wound on a timing pulley which is fixed to a rotary shaft which is supported by the rotatable body such that the rotary shaft is concentric with the rotatable body and is rotatable relative to the same. The rotary shaft is rotated by an electric motor which is attached to the base member.
The intermittently rotatable body is intermittently rotated about the axis line thereof in such a manner that the rotatable body is continuously rotated by an intermittent-rotation angle in a first step and is stopped in a second step and the first and second steps are repeated. The intermittent-rotation angle is equal to the regularly spacing angle at which the component holders are equiangularly spaced from each other about the axis line of the rotatable body. When the rotatable body is rotated, the component holders are sequentially moved to a component receiving position and a component mounting position. At the component receiving position, each of the component holders is lowered and elevated by an elevating and lowering device for taking a CC from a CC supplying device and, at the component mounting position, each component holder is lowered and elevated by another elevating and lowering device for mounting the CC on a CS. Before each component holder mounts the CC on the CS, it is rotated about its axis line. More specifically described, when the rotary shaft is rotated, each of the sleeves is rotated via the timing belt and the corresponding timing pulley, so that the corresponding component holder is rotated. Thus, the CC held by each component holder can be rotated from its initial angular or rotation position when it is taken from the CC supplying device, to a different rotation position at which it is mounted on the CS.
However, in the above CC mounting device, the component holders are held by the intermittently rotatable body via the respective sleeves such that each of the component holders is rotatable and is movable in the axial direction thereof. Accordingly, the rotatable body needs a large size. When each component holder is moved in the axial direction thereof, the corresponding timing pulley must not be moved relative to the timing belt. To this end, the rotatable body is equipped with the sleeves each of which is movable in its axial direction, and is not rotatable, relative to the corresponding component holder and is not movable in its axial direction, and is rotatable, relative to the rotatable body. The rotation of the rotary shaft is transmitted to each component holder via the corresponding is sleeve. Thus, it is very difficult to reduce the size of the rotatable body. Consequently it is difficult to increase the speed of rotation of the rotatable body or improve the efficiency of mounting of CCs.